What does ATOM sell?

I'm curious, could you explain what ATOM actually sells? I've heard about it in the context of cryptocurrency, but I'm not entirely clear on its purpose or the services it offers. Is it a currency in itself, or does it represent some sort of utility or asset? And how does the sale of ATOM fit into the broader ecosystem of finance and cryptocurrency? I'd appreciate it if you could break it down for me in a way that's easy to understand.